Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a controlled study of red cell membrane fatty acids in patients with schizophrenia, substantial depletions of fatty acids from both the n-6 and n-3 series were demonstrated. Arachidonic acid and docosahexaenoic acid were particularly depleted. In a separate study, dietary analysis revealed no deficiency of fatty acid intake in this patient group, but greater intake of n-3 fatty acids was associated with less severe symptomatology. Dietary supplementation for six weeks with 10 g per day of concentrated fish oil (MaxEPA) led to significant improvement in schizophrenic symptoms. This clinical improvement was related to the increased level of n-3 fatty acids in red cell membranes. These findings form part of a growing body of research data suggestive of an abnormality in cell membrane fatty acid composition in schizophrenia. The preliminary evidence for clinically effective dietary manipulation to correct such an abnormality opens up novel and exciting therapeutic possibilities.
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PMID:Fatty acids and schizophrenia. 872 13

During the last few years analyses of the lipidmetabolism have been performed on schizophrenic patients. Anabolic and katabolic metabolite-concentrations from blood and cell samples have been measured. By means of new investigation techniques, such as 31P-magnetic-resonance-spectroscopy, it is nowadays even possible to determine membrane metabolites non-invasively in vivo. Arachidonic acid deficits in peripheral cell membranes, turnover of phosphodiesters in the brain, increased phospholipase A2 (PLA2)-activity in serum and blood cells, disturbed niacin-response and abnormalities of the PLA2-gene are summarised as phospholipid-membrane-hypothesis of schizophrenia. Although there is some evidence for correlations between those findings and psychotic symptoms, the connection to the pathogenesis of schizophrenia still has speculative character. Furthermore it has to be confirmed that peripheral biochemical findings acquired in schizophrenics are transferable to the metabolism of the central nervous system. Actual results of enzyme and metabolite measurements reported in literature and current findings of our own 31P-MR-spectroscopic studies are surveyed and summarised. To point out possible connections between the phospholipid-metabolism of the central nervous system and of peripheral blood-cells, systemic approaches are considered.
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PMID:[Diseases of phospholipid metabolism as possible pathogenetic factors in schizophrenia. Current findings and critical evaluation]. 1094 56

Retinoic acid modulates a wide variety of biological processes including proliferation, differentiation, and apoptosis. It interacts with specific receptors in the nucleus, the retinoic acid receptors (RARs). The molecular mechanism by which retinoic acid mediates cellular differentiation and growth suppression in neural cells remains unknown. However, retinoic acid-induced release of arachidonic acid and its metabolites may play an important role in cell proliferation, differentiation, and apoptosis. In brain tissue, arachidonic acid is mainly released by the action of phospholipase A2 (PLA2) and phospholipase C (PLC)/diacylglycerol lipase pathways. We have used the model of differentiation in LA-N-1 cells induced by retinoic acid. The treatment of LA-N-1 cells with retinoic acid produces an increase in phospholipase A2 activity in the nuclear fraction. The pan retinoic acid receptor antagonist, BMS493, can prevent this increase in phospholipase A2 activity. This suggests that retinoic acid-induced stimulation of phospholipase A2 activity is a retinoic acid receptor-mediated process. LA-N-1 cell nuclei also have phospholipase C and phospholipase D (PLD) activities that are stimulated by retinoic acid. Selective phospholipase C and phospholipase D inhibitors block the stimulation of phospholipase C and phospholipase D activities. Thus, both direct and indirect mechanisms of arachidonic acid release exist in LA-N-1 cell nuclei. Arachidonic acid and its metabolites markedly affect the neurite outgrowth and neurotransmitter release in cells of neuronal and glial origin. We propose that retinoic acid receptors coupled with phospholipases A2, C and D in the nuclear membrane play an important role in the redistribution of arachidonic acid in neuronal and non-nuclear neuronal membranes during differentiation and growth suppression. Abnormal retinoid metabolism may be involved in the downstream transcriptional regulation of phospholipase A2-mediated signal transduction in schizophrenia and Alzheimer disease (AD). The development of new retinoid analogs with diminished toxicity that can cross the blood-brain barrier without harm and can normalize phospholipase A2-mediated signaling will be important in developing pharmacological interventions for these neurological disorders.
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PMID:Retinoic acid-mediated phospholipase A2 signaling in the nucleus. 1521 Mar 3

Although the presence of prostaglandin PGF(2?) has been demonstrated in the central nervous system in the mid sixties, it has taken a rather long time to pinpoint a role of certain metabolites of arachidonic acid in the regulation of neural activity. The modern family of bioactive compounds known as "prostanoids" or "eicosanoids" includes the classical end-products of the cyclooxygenase pathway (prostaglandins, prostacyclin and thromboxane), as well as the molecules formed after the activation of 5- and/or 15-lipoxygenases (leucotrienes and lipoxines), 12-lipoxygenase (hepoxilins) or of epoxygenase (epoxides). Although the brain levels of arachidonic acid-the precursor generating prostaglandins from the series 2-are very low, a plethora of stimuli appears to trigger its release from membrane phospholipids mainly by activation of phospholipase A(2) or subordinately phospholipase C; furthermore, its reesterification can also be subtly regulated by endogenous metabolic processes. Numerous prostanoids have now been detected in the nervous system, namely in neurons, astrocytes, cerebrospinal fluid and cerebral vascular endothelium. Efforts have been oriented at the elucidation of the roles of prostanoids in some physiological conditions (for example sleep regulation) or pathological situations (fever, migraine, epilepsy, schizophrenia). Moreover, several investigators have examined the localization of neuronal membrane receptors for prostanoids and searched for the mechanisms of signal transduction or the identity of second messengers. Those embody cyclic nucleotides (cAMP and cGMP) and calcium. There is also compelling evidence for a modulation by prostanoids of the release of noradrenaline, serotonin and vasoactive intestinal peptide (VIP) as well as of several hormones of the hypothalamic-hypophyseal tract. In addition, neurotransmitters can influence prostanoid synthesis; this has been demonstrated in particular for noradrenaline and more recently for acetylcholine. Prostanoids can also amplify neurotransmitter-mediated signals. Thus, ?(1)-adrenergic agonists, H(1)-histaminergic agonists as well as adenosine potentiate cAMP formation elicited by the VIP, through a concomitant generation of prostaglandins mediated by a direct coupling with phospholipase A(2). Baclofen (a GABA(B)-receptor agonist) exerts a similar potentiation mediated in part by the increased activity of 5-lipoxygenase. Furthermore, eicosanoids generated by 12-lipoxygenase are involved in the histamine- or FMRFamide-induced hyperpolarization (opening of K(+) channels) that has been demonstrated in identified sensory neurons of Aplysia. Finally, the stimulation of N- methyl - d - aspartate receptors (a subclass of glutamate receptors) leads to a release of arachidonic acid as well as of 11- and 12-hydroxyeicosatetraenoic acids in cultured striatal neurons. Arachidonic acid and a large number of its classical or recently discovered metabolites therefore display various effects in the central nervous system, both at the level of integrated processes and of the fine synaptic circuitry, where they can act as intracellular or extracellular local messengers triggering new cascades of short term or long term cellular events.
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PMID:Prostanoids and their role in cell-cell interactions in the central nervous system. 2050 6

Arachidonic acid (AA), an essential polyunsaturated fatty acid, is one of the major components of neural membranes, which show an altered phospholipid composition in schizophrenia. Arachidonate 12-lipoxygenase (ALOX12), an important enzyme, metabolizes AA to 12-HPETE, which affects catecholamine synthesis. However, research has yet to show the genetic association between ALOX12 and schizophrenia. Therefore, we investigated single nucleotide polymorphisms (SNP) of the ALOX12 gene in schizophrenia, recruiting patients with schizophrenia (n = 289) and normal controls (n = 306) from a Korean population. We selected three SNPs (rs1126667, rs434473, and rs1042357) of the ALOX12 gene and genotyped them by direct sequencing. We reviewed the schizophrenic patients' medical records and assessed them clinically using the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Negative Symptoms (SANS), and the Operational Criteria Checklist (OPCRIT). Then we statistically analyzed the genetic associations between the SNPs and schizophrenia, finding a genetic association between both rs1126667 and rs1042357 and schizophrenia, in the recessive model (p = 0.015 and 0.015, respectively). We also found an association between rs434473 and negative symptoms, defined through a factor analysis of the OPCRIT data (p = 0.040). Consequently, we suggest that SNPs of the ALOX12 gene might be associated with schizophrenia and negative symptoms in this Korean population. These weak positives require additional study.
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PMID:Association between polymorphisms of arachidonate 12-lipoxygenase (ALOX12) and schizophrenia in a Korean population. 2062 12

Phospholipases A2 (PLA2) are a diverse group of enzymes that hydrolyze membrane phospholipids into arachidonic acid and lysophospholipids. Arachidonic acid is metabolized to eicosanoids (prostaglandins, leukotrienes, thromboxanes), and lysophospholipids are converted to platelet-activating factors. These lipid mediators play critical roles in the initiation, maintenance, and modulation of neuroinflammation and oxidative stress. Neurological disorders including excitotoxicity; traumatic nerve and brain injury; cerebral ischemia; Alzheimer's disease; Parkinson's disease; multiple sclerosis; experimental allergic encephalitis; pain; depression; bipolar disorder; schizophrenia; and autism are characterized by oxidative stress, inflammatory reactions, alterations in phospholipid metabolism, accumulation of lipid peroxides, and increased activities of brain phospholipase A2 isoforms. Several old and new synthetic inhibitors of PLA2, including fatty acid trifluoromethyl ketones; methyl arachidonyl fluorophosphonate; bromoenol lactone; indole-based inhibitors; pyrrolidine-based inhibitors; amide inhibitors, 2-oxoamides; 1,3-disubstituted propan-2-ones and polyfluoroalkyl ketones as well as phytochemical based PLA2 inhibitors including curcumin, Ginkgo biloba and Centella asiatica extracts have been discovered and used for the treatment of neurological disorders in cell culture and animal model systems. The purpose of this review is to summarize information on selective and potent synthetic inhibitors of PLA2 as well as several PLA2 inhibitors from plants, for treatment of oxidative stress and neuroinflammation associated with the pathogenesis of neurological disorders.
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PMID:Synthetic and natural inhibitors of phospholipases A2: their importance for understanding and treatment of neurological disorders. 2589 85

Arachidonic acid (AA)-derived lipid mediators are called eicosanoids. Eicosanoids have emerged as key regulators of a wide variety of physiological responses and pathological processes, and control important cellular processes. AA can be converted into biologically active compounds by metabolism by cyclooxygenases (COX). Beneficial effect of COX-2 inhibitor celecoxib add-on therapy has been reported in early stage of schizophrenia. Moreover, add-on treatment of celecoxib attenuated refractory depression and bipolar depression. Further, the COX/prostaglandin E pathway play an important role in synaptic plasticity and may be included in pathophysiology in autism spectrum disorders (ASD). In this regard, plasma transferrin, which is an iron mediator related to eicosanoid signaling, may be related to social impairment of ASD. COX-2 is typically induced by inflammatory stimuli in the majority of tissues, and the only isoform responsible for propagating the inflammatory response. Thus, COX-2 inhibitors considered as the best target for Alzheimer's disease.
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PMID:Eicosanoids Derived From Arachidonic Acid and Their Family Prostaglandins and Cyclooxygenase in Psychiatric Disorders. 2652 45